Action server

#ros2   #python   #action  

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Table of Content

Action server

Create action server that use Counter.action custom message declare at custom_interfaces

VSCode action intellisense

Add path to search to python.analysis.extraPaths list in settings.json

{
"python.analysis.extraPaths": [
    "/home/user/ros2_ws/install/action_tutorial_interfaces/local/lib/python3.10/dist-packages"
    ]
}

demo

action_tutorial/my_server.py

import rclpy
from rclpy.action import ActionServer
from rclpy.action.server import ServerGoalHandle
from rclpy.node import Node

from custom_interfaces.action import Counter  # pylint: disable=E0401

TOPIC = "my_action_demo"


class MyNode(Node):
    def __init__(self):
        node_name = "action_server"
        super().__init__(node_name)
        self._action_server = ActionServer(self, Counter, TOPIC, self.execute_callback)
        self.get_logger().info("Hello ROS2")

    def execute_callback(self, goal_handle: ServerGoalHandle):
        feedback_msg = Counter.Feedback()
        for i in range(goal_handle.request.count):
            self.get_logger().info(f"current: {i}")
            feedback_msg.current = i
            goal_handle.publish_feedback(feedback_msg)

        self.get_logger().info("Action ended")
        goal_handle.succeed()

        result = Counter.Result()
        result.total = i
        return result


def main(args=None):
    rclpy.init(args=args)
    node = MyNode()
    try:
        rclpy.spin(node)
    except KeyboardInterrupt:
        print("User exit")
    finally:
        node.destroy_node()
        rclpy.try_shutdown()


if __name__ == "__main__":
    main()

package.xml

<!-- Add dependency to custom_interfaces package -->
<depend>custom_interfaces</depend>

Test

Use ROS cli to run action

ros2 interface show custom_interfaces/action/Counter 
int32 count
---
int32 total
---
int32 current

ros2 action send_goal -f <action_topic> <action messegae> <request part>

ros2 action send_goal -f /my_action_demo custom_interfaces/action/Counter "{count: 5}"

feedback

-f show feedback from server

send_goal

ros2 action send_goal -f /my_action_demo action_tutorial_interfaces/action/MyAction "{count: 5}"
Waiting for an action server to become available...
Sending goal:
     count: 5

Goal accepted with ID: c1129edf0f894012921b849b7948703a

Feedback:
    current: 0

Feedback:
    current: 1

Feedback:
    current: 2

Feedback:
    current: 3

Feedback:
    current: 4

Result:
    total: 4

Goal finished with status: SUCCEEDED